amplifier-inside amplifier-box

Headphone amp for a metal detector.

The RJ has a headphone amplifier that uses a 9 volt battery supply. This serves to provide power to the amplifier output signal that strengthens the metal detector weak signal. The level of the output signal can be adjusted by the volume control knob on the detector.

Without a metal detector headphone amplifier, the output signal in some cases is not sufficient. This causes valuables missed in the search. The changing tone differences in scanning metal objects are not so noticeable to the human ear. With the use of a preamplifier, we can detect a gain of about 20 percent more depth range and a more audible tone difference.



We are proud to announce our new improved headphone/speaker booster RJ-1 which can be used with a wide range of metal detectors. Its compact and lightweight design makes it a winner. In quiet or remote areas where a headphone is not crucial you will now experience the benefit of a speaker system with superior detection rate. No objects will be overlooked with this remarkable and sensitive built-in amplifier.

Our field tests prove that even the smallest objects (0.1 g) can be detected without the need for a headphone. 

We have designed this booster for optimum comfort. The minimum weight is a welcome feature that many metal detector operators will appreciate. The booster can be attached to your belt or jacket using e.g. Velcro clips. Or it can simply integrate in our protective control box cover. Here we even made room for a small high capacity Li-ion battery pack that delivers enough power to operate your metal detector for approximately 4 hours.

For those prospectors who use the original metal detector battery pack we have provided an optional connection cable that can be purchased separately. This cable is optimized for use with the Minelab GPX-4500, 4800 and 5000 models. For older models and other brands you need to inform us so that we can customize the connections.

Below I will explain some features of the headphone/speaker booster.  We always kept in mind that the design should be straightforward and easy to use.


From right to left we have a volume control knob for adjusting the output level for either the built-in speaker or the headphone output.

Next we have a switch to select between the speaker or headphone mode.

Then we have the on/off switch together with a LED indicator.

At the left we have the output cable that connects to the combined input cable of the optional Canon 7,4V 8000mAh Li-ion battery or to the original Minelab battery. (first picture)

Also at the left side of the box we see a headphone output socket where you can plug in an optional headphone.


Please note that the pictures shown below are pre-sales models. The retail box may be slightly different.


   RJ-1 side view

   RJ-1 top view

  Connection cable


The booster has its own battery supply that will last for approximately 100 - 200 operating hours (depending on volume level, mixed use, etc.)  A 9 Volt lithium battery will give you maximum performance.

When the battery life comes to an end, simply open the box and exchange the battery (Preferable use a high quality alkaline or lithium 9V battery).  Warning: Do not use rechargeable batteries !!!

The internal speaker does an excellent job. It provides a loud and clear signal when detecting an object.    

The amplifier itself has been carefully selected after hours of field testing and comparing against other models.

We are pleased with the results. We are confident that this all-in-one solution will bring a smile on the face of any metal detector operator!


   RJ-1 open view





Picture showing a Minelab GPX-4500 control box together with  the RJ-1 and a Canon Li-ion battery pack. All safely packed in our custom designed control box cover.


    RJ-1 operational

 Cover unfolded

Combined set for outdoor use. The heavy external Minelab battery was left at home.


A complete kit or an optional High Capacity Rechargeble Lithium-Ion battery pack (7,2V 8000mAh) + connection cable is now available in our webshop!

Complete kit with our control box cover, RJ-1, battery pack + mains charger + car charger = AU$ 350,00

An extra battery pack = AU$ 100,00